Start with the Rick Atkinson Liberation Trilogy book one An Army at Dawn. Easy to read perspective on the North African Campaign which starts the U.S. involvement with the war.
If you want to start at the beginning of the WWII I would suggest The Rise and Fall of the Third Reich.
The books mentioned above are also quite excellent although you will find its hard to put the entire war into a single volume. Many events are missed or glossed over, strategies are rarely discussed and you lose the personal perspective war has on the population.
For all your War book reading needs I would suggest casematepublishing.com
they cover every era of war and have some hard to find books there.